Optimal Quantum-Enhanced Interferometry Using a Laser Power Source

Lang, Matthias; Caves, Carlton M.

doi:10.1103/physrevlett.111.173601

Cited by 163 publications

(220 citation statements)

References 29 publications

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“…When N t 1, our analytic model predicts that an optimal squeezing parameter of r opt ≈ ln(4N t )/4 yields a minimum sensitivity of φ min ≈ 1/N 3/4 t . This is significantly less than the SQL, and furthermore is the best sensitivity possible in this undepleted regime provided sinh 2 r N t [71,72]. For N t = 10 6 , this gives an enhancement in sensitivity of approximately 32 compared with the SQL, which is equivalent to increasing the total number of atoms by a factor of 10 3 at the SQL.…”

Section: A Complete Quantum State Transfermentioning

confidence: 96%

Squeezed-light-enhanced atom interferometry below the standard quantum limit

et al. 2014

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We investigate the prospect of enhancing the phase sensitivity of atom interferometers in the Mach-Zehnder configuration with squeezed light. Ultimately, this enhancement is achieved by transferring the quantum state of squeezed light to one or more of the atomic input beams, thereby allowing operation below the standard quantum limit. We analyze in detail three specific schemes that utilize (1) single-mode squeezed optical vacuum (i.e., low-frequency squeezing), (2) two-mode squeezed optical vacuum (i.e., high-frequency squeezing) transferred to both atomic inputs, and (3) two-mode squeezed optical vacuum transferred to a single atomic input. Crucially, our analysis considers incomplete quantum state transfer (QST) between the optical and atomic modes, and the effects of depleting the initially prepared atomic source. Unsurprisingly, incomplete QST degrades the sensitivity in all three schemes. We show that by measuring the transmitted photons and using information recycling [Phys. Rev. Lett. 110, 053002 (2013)], the degrading effects of incomplete QST on the sensitivity can be substantially reduced. In particular, information recycling allows scheme (2) to operate at the Heisenberg limit irrespective of the QST efficiency, even when depletion is significant. Although we concentrate on Bosecondensed atomic systems, our scheme is equally applicable to ultracold thermal vapors.

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Section: A Complete Quantum State Transfermentioning

confidence: 96%

Squeezed-light-enhanced atom interferometry below the standard quantum limit

et al. 2014

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“…At this time point, the sensitivities (25) and (42) resemble the precision of the MZI. For this interferometer, the Fisher information for the population imbalance probability (31) saturates the QFI for all states (8) with real coefficients C n [34,35]. A spinsqueezed ground state of the Hamiltonian (21) satisfies this condition, therefore, expressions (25) and (31) must coincide.…”

Section: Estimation From the Population Imbalancementioning

confidence: 99%

Atom interferometer in a double-well potential

Gietka

Chwedeńczuk

2014

Phys. Rev. A

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We present a detailed study of an atom interferometer which can be realized in a double-well potential. We assume that the interferometric phase is imprinted in the presence of coherent tunneling between the wells. We calculate the ultimate bounds for the estimation sensitivity and show how they relate to the precision of the Mach-Zehnder interferometer. The interferometer presented here allows for sub shot-noise sensitivity when fed with the spin-squeezed states with reduced either the relative population imbalance or the relative phase. We also calculate the precision of the estimation from the population imbalance and show that it overcomes the shot-noise level when the entangled squeezed-states are used at the input.

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“…It also makes clear that the state is part of the design, which in the general case must simultaneously be optimized [15]. On the other hand, in many cases the optimization of the measurement and preparation context can be performed separately [16], thus making the SLD Fisher information a powerful calculation tool in such cases.…”

mentioning

confidence: 99%

“…In the context of high precision interferometry, current infrastructure and technology finds that a high-power input laser supplemented by squeezed states [1] is the most practical [5]. This restriction and its limits [16] can be overcome through the data processing resource of creating the absolute optimal NOON state input [23].…”

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confidence: 99%

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Data-processing inequalities for quantum metrology

Ferrie

2014

Phys. Rev. A

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We apply the classical data-processing inequality to quantum metrology to show that manipulating the classical information from a quantum measurement cannot aid in the estimation of parameters encoded in quantum states. We further derive a quantum data-processing inequality to show that coherent manipulation of quantum data also cannot improve the precision in estimation. In addition, we comment on the assumptions necessary to arrive at these inequalities and how they might be avoided, providing insights into enhancement procedures which are not provably wrong. Parameter estimation is an integral part of physics. Quantum metrology refers to the study of the ultimate limits in the accuracy of estimates given the structure imposed by quantum theory [1,2]. Estimation at or near this limit is important for practical objectives such as improving time and frequency standards [3,4] as well as fundamental physics, such as the detection of gravitational waves [5].Researchers have found many novel approaches to quantum metrology using, for example, multipass interferometers [6], machine learning techniques [7], and computational Bayesian statistics [8] as well as new bounds [9,10] in increasingly more general scenarios. Here we supplement these results with one of a different flavor. We provide a very general bound on the estimation accuracy in quantum metrology when noise or data processing (either classical or coherent) is present. Precisely, we give a classical and quantum data processing inequality which shows that estimators based on the raw data are optimal. In other words, processing the data cannot improve quantum metrology. We conclude by showing how to avoid the inequalities with more exotic procedures which can be classed into three conceptually intuitive categories: (1) processing data in a way dependent on the parameter; (2) circumventing an imposed operational restriction; or (3) modifying the dynamics which impart the parameter. Consider a statistical model defining a likelihood function Pr(x|θ ; C). In words, there is an experimental context C whose outcomes are labeled by the random variable x and θ is an unknown parameter to be estimated. For quantum metrology, the goal is estimate a parameter which defines a quantum dynamical process:

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Optimal Quantum-Enhanced Interferometry Using a Laser Power Source

Cited by 163 publications

References 29 publications

Squeezed-light-enhanced atom interferometry below the standard quantum limit

Squeezed-light-enhanced atom interferometry below the standard quantum limit

Atom interferometer in a double-well potential

Data-processing inequalities for quantum metrology

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